Is a Sonos Sun a Sonos Sub, just altered by autocorrect (the bane of human civilization)?
When you say ‘turn off the TV’, do you mean unplugging it, or do you just mean ‘turning it off using the remote’?
Have you checked the TV for firmware updates from Samsung? What year is this TV?
Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and called Sonos Support to discuss it? Don’t post the resulting diagnostic number here, their lawyers get sensitive about GDPR.
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.